Track inspection moves up the agenda
DETAILED technical presentations on a wide range of track and civil engineering topics were given to over 300 delegates who attended the Railway Engineering 2002 conference in London on July 3-4, organised by ECS Publications and sponsored by Railway Gazette International. Many of the 117 papers explored the application of new technologies in track construction and maintenance, with a secondary focus on structures and earthworks. Another session was devoted to power supplies, electrification and signalling.
There was considerable interest in what happens at the wheel-rail interface, and many papers addressed this and related issues. Two tackled the problem of leaf-fall: one proposing a laser-based method of cleaning the rail head, the other suggesting an aerodynamic method with deflectors on the vehicles to blow leaves away from the rail-wheel interface where they are crushed to form a slippery film.
Perhaps more fundamental were papers addressing various forms of rail testing, a topic that continues to attract attention in the wake of the landmark derailment at Hatfield in October 2000. In a keynote address on rail flaw detection, Dr Robin Clark, Vice-President, Engineering, at Sperry Rail Inc, noted that rail testing has changed significantly in the last two or three years. He drew attention to work in North America where the most common and problematical rail flaws are transverse defects, weld defects and vertical split-head defects which together account for 55% of the flaws detected by Sperry each year.
Since January 2001 Sperry has built five road-rail detection vehicles featuring both ultrasonic and induction techniques for use in North America, and two more are to be completed by the end of this year. Last year the company won a contract to build and operate an ultrasonic test vehicle on the Railtrack network, and this is currently being fitted out at Derby.
In a brief review of new technologies being investigated for their ability to detect rail flaws, Clark mentioned low-frequency eddy currents, long-range ultrasound, electromagnetics, radiography, magnetics, magnetostriction and electromagnetic acoustic transducers.
The issue of track inspections to detect other kinds of fault is also up for debate. Coming in the wake of the Potters Bar accident on May 10, caused by missing nuts on the drive stretchers of a set of points, the subject is of particular interest in the UK where increasingly restrictive safety regulations are driving up the costs of maintenance, upgrades and new projects (p395).
A J Savage, Engineering & Safety Director of Carillion Rail, examined the options for mechanisation of track inspections to replace manual patrols. One reason is pressure to eliminate fatalities to track workers, currently averaging two a year, which 'is probably as good as it is going to get'. Savage suggested that 'the only way to improve and drive out fatalities from the trackside is a new approach, involving the almost total separation of people and trains rather than trying to carry out work whilst trains are running.' He went on to say that present manual track patrol methods 'are reaching the limits that are acceptable for staff safety', noting that 'the only way we can deliver compliant patrolling on foot is by taking a considerable number of possessions'. The problems are particularly acute at locations with four or more tracks.
Two inspection trains have been ordered for use in the UK by Eurailscout GB, a joint venture formed by Carillion Rail and Eurailscout bv of the Netherlands. One is a modified DMU car fitted with five cameras, rail lighting and a Trackmon geometry system. The vehicle uses Omnicom's OmniInspector equipment and GPS to locate track defects to an accuracy of